The present invention relates to a mould for composite casting of a one-piece cast tool, which comprises at least a first portion, comprising the working component of the tool and which is manufactured from steel, and a second portion, which comprises the body component of the tool and which is manufactured from grey iron, there being at least one interconnection zone between the steel and the grey iron.
The present invention also relates to a method of manufacturing a mould for composite casting of a one-piece cast tool, which comprises at least a first portion comprising the working component of the tool and which is manufactured from steel and a second portion comprising the body component of the tool and which is manufactured from grey iron, there being at least one interconnection zone between the steel and the grey iron.
In the manufacture of tools for sheet metal working such as cutting, bending or other shaping, it has previously often been the practice to separately produce a tool body of grey iron. This tool body has previously been provided with working components, which carry out the actual operations for which the tool is intended. The manufacture of the tool body takes place by casting, and after the casting, heat treatment of the tool body is often required. This is followed by machining of the tool body in order to realise the requisite seats for the working component or components of the tool, guide stub shafts and bolt holes for fixing them but also to make possible fixing of the tool body in a machine.
In the production of the working component or components which the tool is to have, the point of departure has often been bar material, the working components being machined to the correct shape, provided with apertures for fixing bolts, guide stub shafts and the like. This has normally been followed by heat treatment, whereafter additional machining, for example grinding, is carried out.
Producing a tool in the above-outlined method is extremely time consuming and expensive and is, therefore, often determinative of the time consumption which is required for the new production of different products.
WO 03/041895 discloses a one-piece composite cast tool and a method of its manufacture, where the tool has different material compositions in different parts of the tool. Manufacture according to this publication has, however, encountered major problems in certain respects, for example the formation of a mould model which is to be employed.
It is desirable to design the mould intimated by way of introduction so that it obviates the drawbacks inherent in the prior art technology. In particular, it is desirable to design a mould so that it may be produced at low cost and with high precision. Further, it is desirable to design the mould so that it is possible, without difficulty, to cast material with different coefficients of thermal expansion in one and the same mould.
According to an aspect of the present invention, a mould is characterised in that it comprises at least a first model section corresponding to the first portion and at least a second model section corresponding to the second portion, the first model section being in contact with the second model section along at least one contact plane which is horizontal and planar in the position of use of the mould and which, in the mould, represents the interconnection zone.
According to another aspect of the present invention, a method is characterised in that a first model section is produced corresponding to the first portion, that a second model section is produced corresponding to the second portion, that the sections are given at least one planar contact surface along which they are brought into contact with one another, that the mould is finished with a mould material, the contact surface being aligned to a horizontal position intended for the interconnection zone in the moulding position of the mould and the first model section is positioned lowermost.